Crude oil

A fuel is a substance that, when burned, releases heat energy.A hydrocarbon is a compound made of hydrogen and carbon atoms only.

Complete and incomplete combustion:The possible products of complete and incomplete combustion of hydrocarbons with oxygen in the air are - Carbon dioxide (Complete)Carbon monoxide, which is a toxic gas (Incomplete)Carbon, which forms soot (Incomplete)

You must also understand why carbon monoxide is poisonous, in terms of its effect on the capacity of blood to transport oxygen. This is because the Carbon monoxide reacts to the haemoglobin permanently, as opposed to oxygen which does not react permanently. CO is known as the 'silent killer' because after a person breathes it in, they will have a reduced transport of O2 to the blood and so they will feel tired. They go to bed and then die in their sleep. This happens because CO is colourless and odourless which is the main reason why is it so dangerous.

Crude oil is a mixture of unrefined hydrocarbons. On its own, it is not used as a fuel as it is hard to ignite but by heating it up and putting it into a fractionating column, we can separate the crude oil into more useful substances.​First, the crude oil is heated to around 350-400 degrees celcius so that all of the crude oil is vaporised. The vaporised crude oil then enters the fractionating column. When it starts to cool, the longest molecules condense as they have the highest boiling points, and fall to the bottom of the column. They are then removed as the first fraction.The remaining crude oil vapours rise up through the bubble caps, the smaller molecules rising straight to the top, and the new longest molecules do not rise much. Now the longest molecules will start to condense and will be removed as the second fraction.In this way, the different fractions are separated using the different boing points of the hydrocarbons. Small molecules have low boiling points and large molecules have higher boiling points.After the fractionating has been completed, each fraction will contain a similar range of hydrocarbons.

Refinery gasses are used as bottled gas.

Petrol is used for vehicles such as cars.

Naptha is used to make certain chemicals.

Kerosine is used as plane fuel.

Diesel is used as diesel fuels (for trucks, some cars etc).

Lubricating oils are used as waxes and polishes.

Fuel oil is used for ships and factories.

Bitumen is used for roads and roofing.

To balance well between supply and demand, you can crack the long alkanes from crude oil into a shorter alkane and an alkene. You would do this because shorter alkanes have much more uses than long alkanes, such as the fact that they can be ignited easier.

Here is an example: Octane (C8H18) can be cracked to give a shorter alkane such as Pentane (C5H12) and an alkene, in this case Propene (C3H6)

Acid rain: The products of combustion in air are quite dangerous. In car engines, it is so hot that oxygen in the air can react with nitrogen in the atmosphere to create nitrogen oxides (NOx), and impurities in fossil fuels such as sulphur can react with oxygen when burned to create SO2.In the atmosphere, SO2 reacts with water to create Sulphuric acid (H2SO3).NOx also reacts with water to form Nitric acid (HNO3).

The reason that this is so bad for the environment is because Nitric acid and Sulphuric acid are both acidic and so make the rain fall acidic. The acid rain can wash away nutrients in soil so plants cannot grow properly, it can kill marine life that are sensitive to pH change and even damage leaves of plants so that they can't photosynthesize properly. Thos is especially bad as photosynthesising plants remove CO2 from the atmosphere (which is a greenhouse gas), and so of the plants cannot photosynthesize, less CO2 is removed.

Viscosity and Volatility:We can use the words 'viscosity' and 'volatility' to describe the nature of substances.Viscosity refers to the ease in which something flows, so e.g. tar which is very viscous flows very slow.Volatility refers to the ease in which something can turn into a gas